In modern web development, consuming APIs is a common task. However, it’s important to ensure that API usage is controlled to avoid overwhelming the server and to prevent abuse. One way to achieve this is by implementing rate limiting.

Rate limiting restricts the number of API requests a client can make within a specific timeframe. In this blog post, we will explore how to apply rate limiting using JavaScript Proxy.

What is JavaScript Proxy?

JavaScript Proxy is a feature introduced in ECMAScript 6 that allows us to intercept and customize fundamental operations on objects, including property accesses, function calls, etc. It provides a powerful mechanism to control and modify object behavior.

Implementing rate limiting with JavaScript Proxy

To implement rate limiting, we can create a JavaScript Proxy object that intercepts API requests and applies rate limiting rules. Here’s an example implementation using ES6 syntax:

const createRateLimitedProxy = (target, requestsPerMinute) => {
  const requestHistory = [];

  return new Proxy(target, {
    apply(target, thisArg, args) {
      const currentTime = Date.now();
      const minuteAgo = currentTime - 60000;

      requestHistory.push(currentTime);

      // Remove old requests from the history
      while (requestHistory.length > 0 && requestHistory[0] < minuteAgo) {
        requestHistory.shift();
      }

      // Check if the number of requests exceeds the limit
      if (requestHistory.length > requestsPerMinute) {
        throw new Error('Rate limit exceeded');
      }

      return target.apply(thisArg, args);
    },
  });
};

// Example usage
const targetAPI = () => {
  // Make actual API request here
  console.log('API request made');
};

const rateLimitedAPI = createRateLimitedProxy(targetAPI, 5); // Allow 5 requests per minute

// Make API requests through the rate limited proxy
rateLimitedAPI(); // Success
rateLimitedAPI(); // Success
rateLimitedAPI(); // Success
rateLimitedAPI(); // Success
rateLimitedAPI(); // Success
rateLimitedAPI(); // Throws an Error: Rate limit exceeded

In this example, createRateLimitedProxy is a helper function that takes the target API function and the maximum number of requests allowed per minute as arguments. It creates a Proxy object that intercepts calls to the target API. The Proxy then checks if the number of requests made within the last minute exceeds the limit and throws an error if it does.

By using this rate limiting proxy, you can control and restrict the number of API requests made by your client-side application, preventing abuse and ensuring fair usage.

Conclusion

Rate limiting is an essential technique to manage and control API consumption. By leveraging JavaScript Proxy, we can intercept API requests and enforce rate limits in a straightforward way. This helps ensure the stability and reliability of both the client and the server.

#JavaScript #RateLimiting